Three Things You Didn’t Know About the Arachnids That Live on Your Face

Editor’s Note: This is a guest post by Michelle Trautwein, adjunct assistant professor of entomology at NC State and Schlinger Chair of Dipterology at the California Academy of Sciences.

You are not alone. Your body is a collection of microbes, fungi, viruses…and even other animals. In fact, you aren’t even the only animal using your face. Right now, in the general vicinity of your nose, there are at least two species of microscopic mites living in your pores. You would expect scientists to know quite a lot about these animals (given that we share our faces with them), but we don’t.

Here is what we do know: Demodex mites are microscopic arachnids (relatives of spiders and ticks) that live in and on the skin of mammals – including humans. They have been found on every mammal species where we’ve looked for them, except the platypus and their odd egg-laying relatives.

Often mammals appear to host more than one species, with some poor field mouse species housing four mite species on its face alone. Generally, these mites live out a benign coexistence with their hosts. But if that fine balance is disrupted, they are known to cause mange amongst our furry friends, and skin ailments like rosacea and blepharitis in humans. Most of us are simply content – if unaware – carriers of these spindly, eight-legged pore-dwellers.

Scientists from NC State, the North Carolina Museum of Natural Sciences, and the California Academy of Sciences have just published a study that uncovers some previously unknown truths regarding these little-known mites – all the while providing a glimpse into even bigger mysteries that have yet to be solved.

1. Everyone has mites.

One of our most exciting discoveries is that these mites are living on everyone. Yes everyone (even you). This hasn’t always been obvious because it can be hard to find a microscopic mite living on one’s face. Traditional sampling methods (including scraping or pulling a piece of tape off your face) only return mites on 10-25 percent of adults. The fact that mites are found at a much higher rate on cadavers (likely because the dead are easier to sample more extensively and intrusively) was a hint that they might be much more ubiquitous.

As it turns out, you don’t have to actually see a mite to detect its presence. Dan Fergus, a mite molecular biologist at the North Carolina Museum of Natural Sciences, discovered that mite DNA could be sequenced from face scrapings regardless of whether a mite could be found under the microscope. And mite DNA was sequenced from every adult we sampled. Meaning that if you let us scrape your face, we’d find mite DNA on you as well. And where mite DNA is found, you’ll find mites.

2. Humans host two mite species that aren’t closely related to each other.

One of the most intriguing (and unsolved) face mite mysteries is how humans acquired these beasties. Perhaps these mites are a model system of co-evolution. It’s possible that as every species of mammal evolved, so did their mites – each one particularly adapted to its changed environs. In such a case, we would expect that we acquired our mites from our ape ancestors, and that the two species of human mites would be more closely related to each other than to any other mite species.

However, we’ve learned that the two mite species on our faces Demodex folliculorum (the long skinny one, pictured at the top of this post) and Demodex brevis (the short, chubby one, photo to the right) are actually not very close relatives to each other at all. Our analyses actually show that brevis is more closely related to dog mites than to folliculorum, the other human mite. This is interesting because it shows us that humans have acquired each of these mite species in different ways, and that there are two separate histories of how each of these mite species came to be on our face.

Though we don’t have enough evidence to say that we got one of our mites from man’s best friend, it does seem possible that one of the domestic animal species that we’ve long shared our lives with (be it dogs, goats or otherwise) may have gifted us their mites.

3. Mites can tell us about the historical divergence of human populations

How we acquired our mites is just one part of the story. We are also curious about how our mite species have evolved since they became our constant companions.

Demodex have likely been living with us for a long, long time; as early humans walked out of Africa and found their way around the globe, they probably carried their mites with them. So we want to know if Demodex DNA can provide a reflection of our own evolutionary history by allowing us to retrace those ancient paths of human migration.

So far, our analyses look promising. When looking at the DNA from one of our mite species, D. brevis, we found that mites from China are genetically distinct from mites from the Americas. East Asians and European populations diverged over 40,000 years ago and so far it looks like their mites did as well. On the other hand, D. folliculorum from China is indistinguishable from that of the Americas. Of the two Demodex species associated with humans, D. brevis lives deeper in your pores than folliculorum and is probably shared between people less readily, whereas D. folliculorum appears to enjoy global domination.

But as exciting as these results are, China and the US are just a small piece of the picture. We can’t wait to see what happens when we sample D. brevis from people all over the world! The ancient journey of Homo sapiens as retold by mites.

If reading this made your face a little itchy, rest easy. In an evolutionary perspective, humans and Demodex are old, old friends. You are in good company. And so are your mites.

The paper, “Ubiquity and diversity of human associated Demodex mites,” is published in PLOS ONE. Lead author of the paper is Megan Thoemmes, a Ph.D. student at NC State. Co-authors include Trautwein, Fergus, Julie Urban of the North Carolina Museum of Natural Sciences, and Rob Dunn, an associate professor of biology at NC State. The research was supported by NASA, under grant ROSES NNX09AK22G, and the National Science Foundation, under grant 0953390.

Okay, yes! I looked up a popular treatment and treated my eyelids, eyebrows, and facial pores for several days, because I was sufficiently grossed out. I didn’t even mind the awful burning. Whether his made a difference of not, I feel a LOT better, lol.

Just so you know, it’s completely natural and (generally) healthy to have these mites. It’s actually doing more damage to try and eradicate them from your face (unless they are causing a condition). Trying to get rid of them is akin to trying to kill all the bacteria in your intestines.

You have 17, because two fell off this morning, coincidentally while you were reading this article. I think they felt inadequate after seeing the magnified picture, poor things thought they were supposed to be *that* big 🙁

I’m so glad you are studying this! I’ve wondered about it myself. … I’ve also wondered how the genetic differences in brevis might affect research conclusions from different regions of the world. (Not that there are many papers published about how brevis affects humans other than their role in blepharitis.) … I think it would also be neat to see how the mites of other domestic animals fit into the genetic tree.

Perhaps kindly, the author failed to mention the most disturbing thing about these little critters – they have no anus and so keep “packing it away”, so to speak, for their entire lives (approx 2 weeks on average I believe). And when they finally die they rot away on your skin and their accumulated faeces is released, along with the bacteria that lives in it and them… Good thing they’re microscopic, eh?

At night, while you sleep and remain still for a sufficiently long time, the Demodex mites come out of your pores to look for mates. They mate on your face. Then they crawl back into your pores to lay their fertilized eggs.

Good questions! The answers aren’t entirely clear. They *might* be transferred from mother to infant during nursing. Or they might not. They *might* have beneficial effects (such as eating other little things, like fungi or bacteria, that could do us harm). Or they might not.

We do know that mites, for the most part, don’t hurt us. However, there may be some relation between mites and skin conditions in humans. Again, it’s really not clear.

You can learn more about these mites at the following sites (all are fun reads — at least in my opinion):

I live in New Mexico and cough constantly. Allergies cause me to have an asmtha cough (spasmodic) and it racks my body exhausting me. I have had to have breathing treatments because I would be so sick. One day I turned off the swamp cooler and got better. The cough is due to allergies. So, I can understand what jean jack is talking about.

I wonder if the size of their populations can be affected by certain acne medications meant to shrink and keep your pores clean? I was on a lot of harsh acne meds when I was younger, so I wonder if I killed the poor things off! They’ve got kind of a chubby cuteness to them…

How old are we when we first acquire the mites? And do we exchange mites regularly with other people, e.g. through sneezing, close contact? Reiterating Michael Katz’s question, what benefits do nose mites bring us?

I had these mites bite my forehead and on my eye lashes, so itchy and very uncomfortable. They even caused a blind boils down my chin, so very sore. Doc gave me penicillin tabs and anti biotic cream for my eyes.What causes the “break out”???

I’m seeing comments about removal, and about the little guys paying rent. Personally, unless we prove otherwise I assume they do pay rent. I’d be willing to bet they are. I think it’s not only possible but likely that these mites actually help us. What are they eating? Do they produce waste? If so, how does this waste affect the skin? Before trying to cause a mass extinction on your face (and how long would that last?) You might want to ask the question: what will happen to my skin if this co-evolved species suddenly dies off?

When they die they release toxins and bacteria into our skin, as they die in your pores, no anus so quite a full belly of…. I’m wondering if this wrong diagnosis I had of skin cancer…caused by fungus…couldn’t be directly related…as no cancer now…had a micro dermabrasion facial…saw a cup full of stuff removed from my face…just makes you ask….tea tree oil working good so far…

To Fay – in Europe cancer actually is treated as a fungus, and they alkalize to get rid of it like with baking soda since fungus and parasites thrive in acid bodies which we have especially a lot of in the western world with our diets and chemicals. But I’ve come to believe, even if these bugs are on everyone, we shouldn’t have them. This is because recent studies are linking all kinds of mites (as our immune systems weaken) to cellular damage. Their existence on us could be a big key in aging and disease. I started taking baths in borax and tea tree and other anti-parasitics, all kinds of debris came out of my skin and I’ve felt fabulous for the past year doing this. I used to get migraines a couple times a week and haven’t had one since. My skin looks good, my gray hairs coming in disappeared, I have tons of energy, etc. Just saying, the proof is in the pudding… 🙂

Not sure where you get that idea from, in Europe cancer is treated as…cancer. ie an uncontrolled replication of cells.
Different types of cancer are treated in different ways, but none of them are treated “as a fungus”.
Also, if you don’t like the idea of practically invisible mites living on your face, you’ll probably be terrified to learn that your bowels are full of bacteria. In fact, there’s more bacterial cells in your intestines, than there is human cells in your entire body (bacteria are small).
However, don’t go dosing up on antibiotics, all those bacteria play a key role in helping you digest food, without them you’ll get very ill.

Omg recently found these on me why at times there like not there and other times have have invaded my face and hairline leaving my face well not pleasant and hairloss and like a numb feeling what is happending? How do I ruin of them they r bothing me